1993 Dodge Stealth Coolant Pooling In "Valley Pan&quot

Hello, so heres the deal. I just bought a 1993 Dodge Stealth ES. It has 115,000 miles. Recently after driving the vehicle pretty hard, and for about 1000 miles, I've noticed antifreeze pooling up in the "valley pan" I took it to the shop cause coolant was dripping onto the ground, and I thought perhaps it was the waterpump or thermistat. However after taking it to the shop they said it was neither, and that it was leaking under the plunel or intake manifold? And that they would have to take the top half of the motor off, and that it would cost $200.00 just to diagnose the problem. I don't have alot of money so any help would be appreciated. Thanks!

Ps. My oil is normal color (not milky or discolored) and no smoke of any color is coming out of my exhaust. I also forgot to mention that the car will only start heating up when stopped like at stop light or idleing in the driveway etc.. This will also only happen of course if the coolant level is really low and does not happen if the car is being driven down the road. So other than that it has only gotten hot once becuase I keep the coolant level up.